[NFC] Minor code improvement. Replacing simplifyOnce with simplifyOnceImpl.

[dbakunevich]

Summary

While fixing the bug, it was discovered that the simplifyOnce function returns the value of the simplifyOnceImpl function. Therefore, it was decided to remove the simplifyOnce function and replace all its calls with simplifyOnceImpl.

[mkazantsev]

llvm/lib/Transforms/Utils/SimplifyCFG.cpp

282

Do it vice versa: leave simplifyOnce and remove simplifyOnceImpl.

llvm/lib/Transforms/Utils/SimplifyCFG.cpp

SimplifyCFGOpt(const TargetTransformInfo &TTI, DomTreeUpdater *DTU,
                  const DataLayout &DL, ArrayRef<WeakVH> LoopHeaders,
                  const SimplifyCFGOptions &Opts)
       : TTI(TTI), DTU(DTU), DL(DL), LoopHeaders(LoopHeaders), Options(Opts) {
     assert((!DTU || !DTU->hasPostDomTree()) &&
            "SimplifyCFG is not yet capable of maintaining validity of a "
            "PostDomTree, so don't ask for it.");
   }
 
   bool simplifyOnce(BasicBlock *BB);
-  bool simplifyOnceImpl(BasicBlock *BB);
   bool run(BasicBlock *BB);
 
   // Helper to set Resimplify and return change indication.
   bool requestResimplify() {
     Resimplify = true;
     return true;
   }
 };
for (unsigned i = 0, e = PHI.getNumIncomingValues(); i != e; ++i)
                   { DominatorTree::Delete, Predecessor, BB } });
           return true;
         }
       }
 
   return false;
 }
 
-bool SimplifyCFGOpt::simplifyOnceImpl(BasicBlock *BB) {
+bool SimplifyCFGOpt::simplifyOnce(BasicBlock *BB) {
   bool Changed = false;
 
   assert(BB && BB->getParent() && "Block not embedded in function!");
   assert(BB->getTerminator() && "Degenerate basic block encountered!");
 
   // Remove basic blocks that have no predecessors (except the entry block)...
   // or that just have themself as a predecessor.  These are unreachable.
   if ((pred_empty(BB) && BB != &BB->getParent()->getEntryBlock()) ||
bool SimplifyCFGOpt::simplifyOnce(BasicBlock *BB) {
   case Instruction::IndirectBr:
     Changed |= simplifyIndirectBr(cast<IndirectBrInst>(Terminator));
     break;
   }
 
   return Changed;
 }
 
-bool SimplifyCFGOpt::simplifyOnce(BasicBlock *BB) {
-  bool Changed = simplifyOnceImpl(BB);
-
-  return Changed;
-}
-
 bool SimplifyCFGOpt::run(BasicBlock *BB) {
   bool Changed = false;
 
   // Repeated simplify BB as long as resimplification is requested.
   do {
     Resimplify = false;
 
     // Perform one round of simplifcation. Resimplify flag will be set if